Computer systems typically include a combination of volatile and non-volatile memory. Since volatile memory loses its state when power is removed, some computer systems save all data stored in volatile memory to non-volatile memory in response to a power-off condition. For example, when a user initiates hybernate of a computer system, the data saved on the main random access memory (RAM) of the system is saved to the system hard drive.
In many computer systems, the volatile memory is allocated for multiple uses. For example, half of the storage capacity may be allocated for user data, one quarter of the storage capacity may be unused, and the remaining quarter of storage capacity may be allocated as disk cache. Of the portion of the volatile memory that is allocated for disk cache, typically one half of this storage capacity is designated for being written to the system hard drive. Thus, in some computer systems, the entire volatile memory, including the unused portion and that portion of the disk cache designated for being written to the hard drive, is written to the system hard drive in response to a power-off condition.